Hydra: A Parallel Adaptive Grid Code

We describe the first parallel implementation of an adaptive particle-particle, particle-mesh code with smoothed particle hydrodynamics. Parallelisation of the serial code, ``Hydra'', is achieved by using CRAFT, a Cray proprietary language which allows rapid implementation of a serial code on a parallel machine by allowing global addressing of distributed memory. The collisionless variant of the code has already completed several 16.8 million particle cosmological simulations on a 128 processor Cray T3D whilst the full hydrodynamic code has completed several 4.2 million particle combined gas and dark matter runs. The efficiency of the code now allows parameter-space explorations to be performed routinely using $64^3$ particles of each species. A complete run including gas cooling, from high redshift to the present epoch requires approximately 10 hours on 64 processors. In this paper we present implementation details and results of the performance and scalability of the CRAFT version of Hydra under varying degrees of particle clustering.Comment: 23 pages, LaTex plus encapsulated figure

How the Sando Search Tool Recommends Queries

Developers spend a significant amount of time searching their local codebase. To help them search efficiently, researchers have proposed novel tools that apply state-of-the-art information retrieval algorithms to retrieve relevant code snippets from the local codebase. However, these tools still rely on the developer to craft an effective query, which requires that the developer is familiar with the terms contained in the related code snippets. Our empirical data from a state-of-the-art local code search tool, called Sando, suggests that developers are sometimes unacquainted with their local codebase. In order to bridge the gap between developers and their ever-increasing local codebase, in this paper we demonstrate the recommendation techniques integrated in Sando

Stochastic Substitute Training: A Gray-box Approach to Craft Adversarial Examples Against Gradient Obfuscation Defenses

It has been shown that adversaries can craft example inputs to neural networks which are similar to legitimate inputs but have been created to purposely cause the neural network to misclassify the input. These adversarial examples are crafted, for example, by calculating gradients of a carefully defined loss function with respect to the input. As a countermeasure, some researchers have tried to design robust models by blocking or obfuscating gradients, even in white-box settings. Another line of research proposes introducing a separate detector to attempt to detect adversarial examples. This approach also makes use of gradient obfuscation techniques, for example, to prevent the adversary from trying to fool the detector. In this paper, we introduce stochastic substitute training, a gray-box approach that can craft adversarial examples for defenses which obfuscate gradients. For those defenses that have tried to make models more robust, with our technique, an adversary can craft adversarial examples with no knowledge of the defense. For defenses that attempt to detect the adversarial examples, with our technique, an adversary only needs very limited information about the defense to craft adversarial examples. We demonstrate our technique by applying it against two defenses which make models more robust and two defenses which detect adversarial examples.Comment: Accepted by AISec '18: 11th ACM Workshop on Artificial Intelligence and Security. Source code at https://github.com/S-Mohammad-Hashemi/SS

Code Craft

This exhibition, Code Craft is a web design firm that I created, that uses traditional advertising to promote their services and locations. Code Craft emphasizes the hands on craft of websites and connection to the local community through illustrative posters, booklets, and a client welcome package. There are illustrations used throughout the website, posters, and booklet that creates a more hands-on feel than if photos were used in their place. The posters use a combination of photo realistic illustrations that catch the viewers eye, and a more organic illustration of a map that allows a resting place for the information about the brand. The colors are primarily cool, which communicates a calm and welcoming feeling that aids in the balance from the busy illustrations of the buildings. The combination of the color palette and vector illustrations create a mimic of the flat design of websites. The typeface used throughout the branding is Avenir Next, a sans-serif font that helps maintain the easy-going persona of Code Craft, and creates a connection to the current web world as sans-serif fonts are the most common fonts on the web. Throughout the website and booklet there is more white space being utilized since there is more content to display. The use of white space contributes to the calm and welcoming feeling that the posters also portrayed. A few of the artists whose work inspires me currently are Kate Moross and Alex Estrada. Alex uses very clean and modern designs in her web work, and sticks to a simple color scheme throughout her work. Kate alternatively uses bright and popping colors with no specific color scheme to match her flowing bouncy style. I pull from both of these with a combination of bright popping colors, but a cleaner and more modern design overall

CODE TO CRAFT – BEYOND THE VOXEL

The digital nature of post-industrial societies has profound implications for architectural design, documentation and construction. Digital tools and technologies bridge the representational divide between conception and realization, empowering architects to regain control of the design, fabrication and assemblage processes. This paper will discuss ideas and concepts to facilitate the fabrication of non-standard, context-specific, geometrically complex architecture and components. Two case studies exploring digital fabrication and metal casting will be described alongside implications for the fields of architectural design and construction

Code-Bothy: Mixed reality and craft sustainability

Code-Bothy examines traditional bricklaying using mixed reality technology. Digital design demands a re-examination of how we make. The digital and the manual should not be considered as autonomous but as part of something more reciprocal. One can engage with digital modelling software or can reject all digital tools and make and design by hand, but can we work in between? In the context of mixed-reality fabrication, the real and virtual worlds come together to create a hybrid environment where physical and digital objects are visualised simultaneously and interact with one another in real time. Hybridity of the two is compelling because the digital is often perceived as the future/emergent and the manual as the past/obsolescent. The practice of being digital and manual is on the one hand procedural and systematic, on the other textural and indexical. Working digitally and manually is about exploring areas in design and making: manual production and digital input can work together to allow for the conservation of crafts, while digital fabrication can be advanced with the help of manual craftsmanship

Parallelization of a Code for the Simulation of Self-gravitating Systems in Astrophysics. Preliminary Speed-up Results

We have preliminary results on the parallelization of a Tree-Code for evaluating gravitational forces in N-body astrophysical systems. For our Cray T3D/CRAFT implementation, we have obtained an encouraging speed-up behavior, which reaches a value of 37 with 64 processor elements (PEs). According to the Amdahl'law, this means that about 99% of the code is actually parallelized. The speed-up tests regarded the evaluation of the forces among N = 130,369 particles distributed scaling the actual distribution of a sample of galaxies seen in the Northern sky hemisphere. Parallelization of the time integration of the trajectories, which has not yet been taken into account, is both easier to implement and not as fundamental.Comment: 14 pages LaTeX + 1 EPS figure + 2 EPS colour figures, epsf.sty and aasms4.sty included; to be published in Science & Supercomputing at CINECA, Report 1997 (Bologna, Italy

Developing Tools for Multimessenger Gravitational Wave Astronomy

We present work in progress to craft open-sourced numerical tools that will enable the calculation of electromagnetic counterparts to gravitational waveforms: the {\tt GiRaFFE} (General Relativistic Force-Free Electrodynamics) code. {\tt GiRaFFE} numerically solves the general relativistic magnetohydrodynamics system of equations in the force-free limit, to model the magnetospheres surrounding compact binaries, in order (1) to characterize the nonlinear interaction between the source and its surrounding magnetosphere, and (2) to evaluate the electromagnetic counterparts of gravitational waves, including the production of collimated jets. We apply this code to various configurations of spinning black holes immersed in external magnetic field, in order to both test our implementation, and to explore the effect of strong gravitational field, high spins and of misalignment between the magnetic field lines an black hole spin, on the electromagnetic output and the collimation of Poynting jets. We will extend our work to collisions of black holes immersed in external magnetic field, which are prime candidates for coincident detection in both gravitational and electromagnetic spectra.Comment: 6 pages, 6 figures, MG15 proceeding

After Carter v. Canada

When it recently struck down the Criminal Code prohibitions on physician-assisted dying, the Supreme Court of Canada gave federal and provincial legislatures 12 months to craft new legislation to meet the conditions set out in its landmark ruling